How many crees?

[crackerkorean]

How many cree or seoul lights would you need to have enough light to do trail riding?

I am working on a triple for my handle bar and one for my helmet @ 1000ma.

Would two be enough? I know its not as much light but would give better run time.

Or is there a good way to switch on and off individual leds? For example Ican run on two at 500ma until I need more light and then I can kick on the third. And then kick it to 1000ma for tons more light.

 

[georges80]

How many cree or seoul lights would you need to have enough light to do trail riding?

I am working on a triple for my handle bar and one for my helmet @ 1000ma.

Would two be enough? I know its not as much light but would give better run time.

Or is there a good way to switch on and off individual leds? For example Ican run on two at 500ma until I need more light and then I can kick on the third. And then kick it to 1000ma for tons more light.

It's more efficient to dim 3 LEDs than to turn one off.
e.g. 3 LEDs driven at 333mA will be brighter than two driven at 500mA (ASSUMING the same LEDs).

That's the whole point of drivers like bFlex and nFlex - you dim (reduce the current) to all the LEDs rather than driving just one hard.

The only reason to turn off a LED is if the optics on that one LED provided a very different beam pattern that was only required in certain situations.

3 Crees (Q5 e.g.) will put out a huge amount of light at even 750mA and they will put out more than 1/2 that amount of light at 1/2 the current - again due to better efficiency at lower currents.

Finally, driving the LEDs at 1000mA will not be a "ton" more light than at 500mA. First you won't get double the lumens (beaten to death above) AND your eyes are NOT linear. You need close to 10x the lumens to appear twice as bright. The log response of the human eye is the reason that bFlex and nFlex have a log table for dimming.

cheers,
george.

 

[crackerkorean]

Ok that makes sense. I was just curious about getting the best runtime that I can from LEDs. And wasnt sure if i would just reduce the number of LEDs along with reducing the consumed power if it would make that much of a difference.

I am building a light with three seouls and a bflex.

Thanks for the insight I will just keep using the same recipe that works. Since I have yet to see what the LEDs look like I am going to have to wait till its built.

 

[Darell]

And wasnt sure if i would just reduce the number of LEDs along with reducing the consumed power if it would make that much of a difference.

Just in case you missed it... the answer is to use as many emitters as possible, running at the lowest current possible. The difference in power consumption (and heat!) is significant. Use more emitters running lower, and you'll have the best of everything.

 

[imageicon]

i been doing alot of trail riding with 2 cree xr-e on bar and 2 on helmet
that is plenty light. rode 3 24h mtb races this year with that setup.

everyone was amazed with the small form factor and the amount of light they emit. probaly one of the most powerfull setups i have seen during the races..
only a few hid guys matching it and 2 lights beats 1 brigher light anyday.

i am however building a triple Q5 light for my bar mostly because i love making lights, as i already have a triple seoul. but really prefer my 2x2 cree setup.

 

[yellow]

The nightrides I visited so far, have shown quite a bunch of high- to low-class to selfmade lights.
My single Cree @ 1 A was under the three brightest of lights every time, more light usually comes from a Lupine nightmare.

Together with the headlamp (a Streamlight Argo HP) it is more than enough for heavy riding

(imho with much more light one looses that general night feeling - but I am on finishing the three- and the quad-setup in short)

 

[crackerkorean]

IMHO you cant never have enough light. I am blind in one eye so my depth perception is already messed up (makes riding single track tons of fun) so riding at night I need all the help that I can get.

For now I will finish my two triples that I have planned and maybe go for a quad.
Just out of curosity what kind of voltage do you need forthe quad? I will be running a 14.8v on my triple with a bflex would htis work for the quad?

 

[yellow]

I tend to plan not to use "direct drive"-like numbers...

see it this way:
1 Li-Ion = 1 led
1 Circuit = nearly 1 led
and never get even number of emitters and batts

options:
4 Li-Ions (14.4 V) --> 3 leds + step-down circuit (or 5 leds + step-up)
2 Li-Ions --> 1 led + step-down (or at least 3 emitters + step-up)

wiring of multiple emitters ALWAYS in series and use a circuit able to dim them (taskled, or Sandwich Shoppe's SHARK + REMORA)

PS. the BFlex wont work with a quad as what the hp says.
(thats the example of not getting an even number --> 4 emitters, 4 Li-Ions)